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Semiconductor sensing device for fluids

  • US 3,999,122 A
  • Filed: 02/14/1975
  • Issued: 12/21/1976
  • Est. Priority Date: 02/14/1974
  • Status: Expired due to Term
First Claim
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1. A sensor device for detecting fluid substances, comprising:

  • a substrate of an inorganic insulating material,an epitaxially grown layer of an inorganic semiconductor material on a surface of said substrate,a source zone and a spaced-apart drain zone of a given conductivity type on said epitaxially grown layer and a channel zone of said conductivity type interconnecting said drain and source zones with one another,an electrical lead on each of said drain and source zones for interconnecting said sensor device with an operational electrical circuit,a relatively thin layer of a reactive organic material capable of reversible interaction with fluid substances being detected, said organic material being selected from the group consisting of carotenoids, proteins, phthalocyanines, polyvinyl chlorides, polypropylenes, cellulose acetate and mixtures thereof, said layer being in direct contact with a free surface of said epitaxially grown layer,whereby upon energization of said sensor device in the presence of a fluid substance, a reversible reaction occurs between said substance and said organic material and causes a reversible change in the surface potential of said layer due to a field effect and causes a reversible change in the resistance of said channel zone so that the drain current of said sensor is changed.

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